feat: Implement Indexed builder

[zonca]

As discussed with @jpivarski and @ManasviGoyal, here is the implementation of the Indexed layout builder.
The final objective is to use this for EnumType instead of using NumpyBuilder.

[codecov]

Codecov Report

Merging #2883 (6d31acc) into main (9400780) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

[jpivarski]

I approved this on zonca#3, and see that it's the same Indexed Builder implementation here.

This doesn't have the

- cmake -B build -S header-only -DCMAKE_RUNTIME_OUTPUT_DIRECTORY=bin -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTS=ON
+ cmake -B build -S header-only -DCMAKE_RUNTIME_OUTPUT_DIRECTORY=bin -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTS=ON

update in .github/workflows/header-only-test.yml, but that's unrelated to adding the new Builder, so it's best not to have it in the PR, anyway. Everything else looks goo. (The zonca#3 was a difference after IndexedOption had been copied to Indexed, but this is a more direct addition.)

I'll merge it when the tests pass.

[jpivarski]

We only need one approval for merging. Last time, @ManasviGoyal also approved it, anyway.

[zonca]

I approved this on zonca#3, and see that it's the same Indexed Builder implementation here.

This doesn't have the

- cmake -B build -S header-only -DCMAKE_RUNTIME_OUTPUT_DIRECTORY=bin -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTS=ON
+ cmake -B build -S header-only -DCMAKE_RUNTIME_OUTPUT_DIRECTORY=bin -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTS=ON

update in .github/workflows/header-only-test.yml, but that's unrelated to adding the new Builder, so it's best not to have it in the PR, anyway. Everything else looks goo. (The zonca#3 was a difference after IndexedOption had been copied to Indexed, but this is a more direct addition.)

right, that was already merged back in #2870

[jpivarski]

@all-contributors please add @zonca for code

[allcontributors]

@jpivarski

I've put up a pull request to add @zonca! 🎉